Iodine

Iodine/Drug Interactions:

  • AmiodaroneAmiodarone: Amiodarone (Cordarone?) contains significant amounts of iodine (127).
  • Angiotensin-converting enzyme inhibitorsAngiotensin-converting enzyme inhibitors: Concomitant use of angiotensin-converting enzyme inhibitors (benazepril, captopril, enalapril, fosinopril, lisinopril, moexipril, perindopril, quinapril, ramipril, trandolapril) or angiotensin receptor blockers (losartan, valsartan, irbesartan, candesartan, telmisartan, eprosartan) with potassium iodide may increase the risk of hyperkalemia (high blood potassium levels), according to secondary sources.
  • AntibioticsAntibiotics: Antibacterial effects of iodine have been demonstrated in various in vitro, laboratory, and human studies (243; 244; 245; 246; 247).
  • AnticoagulantsAnticoagulants: The use of pharmacologic doses of potassium iodide may decrease the anticoagulant effect of warfarin (Coumadin?), according to secondary sources.
  • AntineoplasticsAntineoplastics: It is unclear whether iodine is effective in the prevention or treatment of cancer. Antioxidant and antitumor effects have been proposed, based on laboratory research. In contrast, some scientists have asserted that tumors may uptake more iodine than normal tissues. Iodine may be used as an adjuvant therapy for node-negative colonic cancer (248). In Poland, the institution of household salt iodization was associated with a decrease in the standardized incidence ratio of stomach cancer from 19.1 per 100,000 to 15.7 per 100,000 in men, and from 8.3 per 100,000 to 5.9 per 100,000 in women (249). Overall, a clear conclusion cannot be drawn based on the currently available evidence.
  • Cardiovascular agentsCardiovascular agents: According to secondary sources, hypersensitivity reactions to iodine may involve cutaneous or mucosal hemorrhage, vasculitis, or severe periarteritis. Weak pulse has been reported as a symptom of acute iodine poisoning, according to secondary sources. According to human research, excessive iodine intake may cause atrial fibrillation (122; 123).
  • Lithium saltsLithium salts: According to review data, additive hypothyroid effects may occur with the use of iodine products such as potassium iodide and Lugol solution in combination with lithium salts (129).
  • MetronidazoleMetronidazole: In clinical research, children with intestinal parasitic infestations treated with metronidazole experienced reduced efficacy of oral supplementation with iodized ethyl esters by interfering with its absorption (130).
  • Neurologic agentsNeurologic agents: Iodine is required for the production of thyroid hormones, which are necessary for normal brain development and cognition. Prolonged iodine deficiency leads to learning disabilities and poor motivation to achieve in children (250). Several randomized controlled trials and reviews have shown that iodine supplementation improved perceptual reasoning, information processing, fine motor skills, and visual problem solving in mild, moderately, and severely iodine-deficient children (202; 251; 252; 253; 126). Headache occurred in some iodine deficient children after iodine supplementation (126). According to secondary sources, depression may be intensified in individuals that take high amounts of iodine.
  • PerchloratePerchlorate: According to review data, perchlorate inhibits the uptake of iodide into the thyroid gland (132).
  • Potassium-sparing diureticsPotassium-sparing diuretics: Concomitant use of potassium iodide with potassium-sparing diuretics may increase the risk of hyperkalemia, according to secondary sources. Examples of potassium-sparing diuretics include spironolactone, triamterene, and amiloride.
  • Thyroid hormone antagonistsThyroid hormone antagonists: Theoretically, additive hypothyroid effects may occur with the use of iodine products in combination with antithyroid drugs (methimazole, propylthiouracil). Both excess iodine intake and iodine deficiency have similar symptoms: elevated thyroid-stimulating hormone (TSH) level and hypothyroidism, which can produce goiter (134). Iodine deficiency or surplus may cause enlargement of the thyroid gland (70). Excessive iodine intake may also cause thyroiditis, thyroid papillary cancer, and thyrotoxicosis (122; 123). Iodine-induced hyperthyroidism, resulting from high iodine intake, has been observed in some areas that use iodized salt (the Jod-Basedow phenomenon) (139; 140; 141).
  • Thyroid hormonesThyroid hormones: Both excess iodine intake and iodine deficiency have similar symptoms: elevated thyroid-stimulating hormone (TSH) level and hypothyroidism, which can produce goiter (134). Iodine deficiency or surplus may cause enlargement of the thyroid gland (70). Excessive iodine intake may also cause thyroiditis, thyroid papillary cancer, and thyrotoxicosis (122; 123). Iodine-induced hyperthyroidism, resulting from high iodine intake, has been observed in some areas that use iodized salt (the Jod-Basedow phenomenon) (139; 140; 141).

    • Iodine/Herb/Supplement Interactions:

  • Angiotensin-converting enzyme inhibitorsAngiotensin-converting enzyme inhibitors: Concomitant use of angiotensin-converting enzyme inhibitors or angiotensin receptor blockers with potassium iodide may increase the risk of hyperkalemia, according to secondary sources.
  • AntiarrhythmicsAntiarrhythmics: Amiodarone (Cordarone?) contains significant amounts of iodine (127).
  • AntibioticsAntibiotics: Antibacterial effects of iodine have been demonstrated in various in vitro, laboratory, and human studies (243; 244; 245; 246; 247).
  • AnticoagulantsAnticoagulants: The use of pharmacologic doses of potassium iodide may decrease the effect of anticoagulant agents, according to secondary sources.
  • AntineoplasticsAntineoplastics: It is unclear whether iodine is effective in the prevention or treatment of cancer. Antioxidant and antitumor effects have been proposed, based on laboratory research. In contrast, some scientists have asserted that tumors may uptake more iodine than normal tissues. Iodine may be used as an adjuvant therapy for node-negative colonic cancer (248). In Poland, the institution of household salt iodization was associated with a decrease in the standardized incidence ratio of stomach cancer, from 19.1 per 100,000 to 15.7 per 100,000 in men, and from 8.3 per 100,000 to 5.9 per 100,000 in women (249). Overall, a clear conclusion cannot be drawn based on the currently available evidence.
  • BugleweedBugleweed: Bugleweed (Lycopus virginicus, Lycopus europaeus) may reduce iodine uptake, according to secondary sources.
  • Cardiovascular agentsCardiovascular agents: According to secondary sources, hypersensitivity reactions to iodine may involve cutaneous or mucosal hemorrhage, vasculitis, or severe periarteritis. Weak pulse has been reported as a symptom of acute iodine poisoning, according to secondary sources. According to human research, excessive iodine intake may cause atrial fibrillation (122; 123).
  • IronIron: According to review data, iron deficiency may exacerbate the effects of iodine deficiency (128). Goitrous children with iron deficiency anemia experienced an impaired therapeutic response to oral iodine (131).
  • LithospermumLithospermum: Ingestion of Lithospermum may lower thyroid hormone blood levels and may interact with the effects of iodine on thyroid hormone levels, according to secondary sources.
  • Neurologic agentsNeurologic agents: Iodine is required for the production of thyroid hormones, which are necessary for normal brain development and cognition. Prolonged iodine deficiency leads to learning disabilities and poor motivation to achieve in children (250). Several randomized controlled trials and reviews have shown that iodine supplementation improved perceptual reasoning, information processing, fine motor skills, and visual problem solving in mild, moderately, and severely iodine-deficient children (202; 251; 252; 253; 126). Headache occurred in some iodine-deficient children after iodine supplementation (126). According to secondary sources, depression may be intensified in individuals that take high amounts of iodine.
  • PotassiumPotassium: Concomitant use of potassium iodide with potassium salts may increase the risk of hyperkalemia.
  • SeaweedSeaweed: Kelp, seaweed, and bladderwrack have been shown to contain high iodine levels.
  • SeleniumSelenium: According to review data, selenium deficiency may exacerbate the effects of iodine deficiency (127). However, human supplementation with selenium and iodine did not result in a synergistic action of selenium and iodine on thyroid function (254).
  • Thyroid agentsThyroid agents: Theoretically, additive hypothyroid effects may occur with the use of iodine products in combination with antithyroid drugs (methimazole, propylthiouracil). Both excess iodine intake and iodine deficiency have similar symptoms: elevated thyroid-stimulating hormone (TSH) level and hypothyroidism, which can produce goiter (134). Iodine deficiency or surplus may cause enlargement of the thyroid gland (70). Excessive iodine intake may also cause thyroiditis, thyroid papillary cancer, and thyrotoxicosis (122; 123). Iodine-induced hyperthyroidism, resulting from high iodine intake, has been observed in some areas that use iodized salt (the so-called Jod-Basedow phenomenon) (139; 140; 141).
  • Vitamin AVitamin A: According to review data, vitamin A deficiency may exacerbate the effects of iodine deficiency and alter the response to iodine supplementation (128). Vitamin A supplementation in iodine-deficient African children decreased thyrotropin stimulation of the thyroid and reduced the goiter rate (255).
  • ZincZinc: According to a review, there is limited evidence describing interactions between iodine and zinc metabolism (256).

    • Iodine/Food Interactions:

  • Cruciferous vegetablesCruciferous vegetables: According to review data, goitrogens, present in high levels in cassava, cabbage, broccoli, cauliflower, and other cruciferous vegetables, interfere with the uptake of iodine in the thyroid (257).
  • SeaweedSeaweed: Kelp, seaweed, and bladderwrack have been shown to contain high iodine levels.

    • Iodine/Lab Interactions:

  • Bleeding timeBleeding time: The use of pharmacologic doses of potassium iodide may decrease the effect of anticoagulant agents. In human research, povidone-iodine significantly controlled bleeding in oral surgery when compared to saline (p<0.01) (167).
  • Heart rhythmHeart rhythm: According to human research, excessive iodine intake may cause atrial fibrillation (122; 123). Amiodarone (Cordarone?) contains significant amounts of iodine (127).
  • Neonatal thyroid-stimulating hormone (TSH) screeningNeonatal thyroid-stimulating hormone (TSH) screening: TSH screening has been used to assess the iodine nutrition of neonates, although there is controversy over whether this is an accurate method. According to preliminary human research, TSH results in newborns may be misleading, because the newborn may absorb iodine when iodine-containing antiseptics are used during labor (81). It has been suggested that neonatal TSH screening using cord sera may be a better method for determining iodine status in newborns (82). According to preliminary human research, the frequency of newborn thyrotropin concentrations >5mU/L may be used to determine iodine nutrition during pregnancy (35).
  • Potassium levelsPotassium levels: Concomitant use of potassium iodide with potassium-sparing diuretics, ACE inhibitors, or potassium salts may increase the risk of hyperkalemia, according to secondary sources.
  • PulsePulse: According to the Institute of Medicine, weak pulse has been reported as a symptom of acute iodine poisoning, according to secondary sources.
  • Thyroid panelThyroid panel: Both excess iodine intake and iodine deficiency have similar symptoms: elevated thyroid-stimulating hormone (TSH) level and hypothyroidism, which can produce goiter (134). Iodine deficiency or surplus may cause enlargement of the thyroid gland (70). Excessive iodine intake may also cause thyroiditis, thyroid papillary cancer, and thyrotoxicosis (122; 123). Iodine-induced hyperthyroidism, resulting from high iodine intake, has been observed in some areas that use iodized salt (the so-called Jod-Basedow phenomenon) (139; 140; 141).
  • Urinary iodine levelsUrinary iodine levels: Iodine status is typically assessed using urinary iodine concentrations (mcg/L) or 24-hour urinary iodine excretion (mcg/24 hours). These two measurements are not interchangeable. It has been noted that urinary iodine excretion is influenced by the intake of dairy products, eggs, iodine-containing supplements, iodized salt, fruits and vegetables, and seafood, as well as by hydration status (76; 77). It has been suggested that urinary iodine may also vary significantly during the day and between days, which may be related to urinary sodium content (79; 80).